Enhanced Electrical Conductivity of (001) Oriented Sr0.9La0.1TiO3 Microplatelets for Thermoelectric Applications.

Abstract

Two-dimensional perovskite microplatelets have played an important role in various applications, especially acting as a template to guide grains' epitaxial growth in the preparation of textured ceramics. The (001) oriented Sr0.9La0.1TiO3 microplatelets with a high aspect ratio of ∼20 were synthesized and obtained from Aurivillius Bi4Ti3O12 precursors. To reveal the mechanism of topochemical microcrystal conversion of Bi4Ti3O12 to Sr0.9La0.1TiO3, the reaction interface, morphology development, and phase composition evolution of the (001) oriented Sr0.9La0.1TiO3 microplatelets were investigated. When the temperature of the molten salt is above 753 °C, multiple Sr0.9La0.1TiO3 topological nucleation events took place. At 950 °C, the polycrystalline aggregate of (001)-oriented Sr0.9La0.1TiO3 crystallites grew in place of the original single crystal Bi4Ti3O12 platelets. When the temperature reached 1150 °C, the Sr0.9La0.1TiO3 platelets preserved the shape of a high aspect ratio and exhibited not only enhanced electrical conductivity with a carrier concentration of 3.518 × 1020 cm-3 and carrier mobility of 8.460 cm2·V-1·s-1 but also significantly decreased thermal conductivity ranging from 5.65 W·m-1·K-1 at 300 K to 2.54 W·m-1·K-1 at 1073 K. It can be widely applied in the field of template grain growth methods for preparing textured thermoelectric ceramics to improve their thermoelectric properties.